Baseboard heater construction



Sept. 29, 1953 w. w. HIcKs 2,654,017

BASEBOARD HEATER CONSTRUCTION Filed Feb. 5, 1951 :ik Y

Flrm45 IN VEN TOR. PV/Y//am fes/eg H/Ic/s A TTR/VEVS Patented Sept. 29, 1953 UNITED STATES PATENT OFFICE 2,654,017 BASEBOARD HEATER CONSTRUCTION William Wesley Hicks, San Francisco, Calif., as-

signor to Ionics, Inc., S

corporation of Californi Application February 5, 1951, Serial No. 209,435

2 Claims.

This invention relates generally to devices for preventing dust particles from adhering to the walls of a room.

Everyone is aware of the smudge created by dirt deposited upon a wall or ceiling immediately adjacent a baseboard heater or other heater which is mounted on the wall or the smudge which is deposited on a wall immediately above a heater outlet. Various devices have been utilized in an attempt to eliminate these smudges but they have in the main been unsatisfactory. Such prior devices include electrical precipitators which are designed to dispose of the dirt which creates the smudge precipitating the same within the device. These devices rely upon the use of extensive and expensive equipment which is at best extremely sensitive and requires proper design, proper electric potentials and proper air velocity. The change in the electric potentials or an increase in the air velocity reduces the eniciency of these devices substantially and after a point, for practical purposes, they are unsatisfactory for the purposes intended.

Furthermore, some of the devices require ideal conditions which in actual fact do not exist. These devices rely upon the assumption that the removal of approximately 90% of the dust will be sufficient, ignoring the fact that a space charge will be built up within a room and that there will be a resulting force on charged particles of dust which will propel them toward the wall thereby causing them to be deposited upon the wall with resulting smudge. The residual space charge is objectionable. A more satisfactory solution is perfected in my invention which is to remove the charge on some of the particles rather than to remove the particles themselves. I have found that the circuiation of dust particles around a room will be determined by both the currents of the air and the electrostatic field resulting from the space charge that might exist.

It is an object of my present invention to provide a smudge eliminator which is adapted to be incorporated in a conventional electric baseboard heater or panel heater of the type which consists generally of a low panel extending along at least one wall of a room.

It is a further object of this invention to provide a combined air heater and device which will eliminate the accumulation of smudge immediately above the heating panel.

It is a further object of this invention to provide a device of this character which may be utilized generally in connection with baseboard an Francisco, Calif., a

2 or panel heaters which are presently on the market.

Other objects and advantages of the present invention will appear from the following specincation taken in conjunction with the accompanying drawings in which:

Figure 1 is a front view of a base board heater construction incorporating my invention;

Figure 2 is a cross-sectional elevation taken along the line 2-2 of Figure 1;

Figure 3 is a cross-sectional detail similar to the View illustrated in Figure 2 and showing one modiiication of the invention; and

Figure l is a circuit diagram showing the method of connecting my baseboard heater and its various components.

As shown in the drawings a baseboard heater is adapted to be mounted along the base of a wall of a room adjacent to the floor I0 within a recess Il in a wall l2. The heater consists generally of a backing plate I3 which may be secured to studding I4 behind the wall surface I2 in any suitable manner. Plate I3 supports the remainder of the heater.

A face plate I6 is provided which, as shown, is generally spaced from the backing plate I3 to form a longitudinal inlet opening Il, at the lower edge of the device and a longitudinal outlet opening IS at the upper edge of the device. Within the space between the backing plate I3 and the face plate I6, I have mounted a vertical baile 2| which may be secured to the device in any conventional manner as by spacers 22. The baille 2| retains the supports 23 for a pair of heating elements 2d and 26. The heating elements 24 and 26 are preferably electric elements.

Located within the stream of the convection currents of air passing through the heating device there is an electric conductor 28. This conductor is adapted to he maintained at a negative potential by suitable electric means connected to the same.

Figure 4 illustrates a suitable electric circuit for making connection between the various electric elements in which the heating elements 24 and 26 are adapted to be energized by a suitable source of alternating current. The supply lines L-I and L-2, which represent lines supplying ordinary house current of either or 220 volts, are connected to the heating elements and also to a rectifier 3s. The negative side or" the rectifier is connected to the conductor 28. The walls i3, I5 and 2! are grounded. As indicated diagrammatically in Figure 4, the conductor 28 is 3 located in the path of now of convection currents of heated air from the element 2li.

A particle such as a dust particle, if carrying electrical charge of either positve or negative polarity, will tend to move away from another electric charge of like polarity and toward another electric charge of unlike polarity. Thus, a positively charged dust particlev floating freely in air `will move away from a region or surface containing positive electrical charge, and toward a region or surface containing negative electrical charge. In other words, there is force on a charged particle that is in an electric field.

An uncharged or electrically neutral/ particle will have no such tendency. UItwillnotlcie acted.

electric charge. Expressed on by the presence of in other words, there will beno force on aneutral particle in a uniform electric held.

emission of positive ions greatly exceeds the emission of negative ions.

In a room containing ordinary air with normal ionization, with the number of positive ions per unit volume exceeding the number of negative ions per unit volume, there is a net positive charge in the space of the room equal to the eX- cess of the positive charge over the negative charge. This i'scalled the net positive space charge. This space charge is attached to ions of air or to particles of dust or moisture in the air. It is distributed throughout the space of the -room.

Thesnetpostivesp-ace charge induces an equal andoppo site charge, a charge of negative polarity,

onthewalls orceiling and oor I of the room.

Theamount of .thecharge on the walls l2, ceil- In ordinary air, in any ordinary room, thatdoes. ,f

not have devices for either increasing or decreasing the amount'of natural. ionization, there are electrical charges resulting from natural ionization such as traces of radioactivity and cosmic rays. These charges `are called ions; they are particles of` various sizes suspended in the air, the largest being particles of dust or moisture and the smallest 4that can exist forl any appreciable length of time being the size of one or more air molecules. There is a tendency for such ions to attach `themselves to dust or moisture particles if there are anysuch particles present in the air. Dust particles may be as small as 1/ 10,000 millimeter in diameter orless, and they may be as large as to 50 thousandths of a millimeter. Air molecules are of the order of 3 107 millimeters in diameter. Ihefusual average number of such ionsin ordinary air varies from a few hundredl 'to one or twol thousand per cubic centimeter of air. Thepresence of these is not appreciable except by electrical test.V However, they can be measured with appropriate apparatus.

.If therlumber espositive .ions-,a.siven volume of air is equal to the number of4 negative ions in that volume, the resulting mixture has no net electrical charge. It is, onthe who1e,'ele,ctrically neutral. If such a volume of air werefree from outside influences, the positive and negative particles would in course of time come intok contact withsah Othelanl! the-individual; charges-.would neutralize each other. This'process of neutralization of individual ions takes place slowly, and a region of air maycontain a mixture of positive and negative ions for aconsiderable length-.oftirne. It is usual, in any ordinary room, during ordinary weather, for the number of positiveions per yunit volume of air to exceed the number of negative, ions perunitvolumze., Thusr tl'iere` may be 500 negative ions perv cubic centimeter and 800 positive ions per cubic centimeter; these are reasonable numbers, but on another` day, with different weather conditions, ,fthe number Yof each polarity of ions may be twice as great.

A piece of metal, such as the wire, forming the electric heater elements 24 and 2B, when heated to the temperature ofV dull red heat, emits positive ions into the surrounding air. At a somewhat higher temperature (the exact temperatures of ion emission ydependen the matel'aland on the condition of its surface) Vthemetaalso emits electrons which quickly vform negative ions in the air. However, my electric heater ordinarily operates at a temperature at which the ing `and floor l0 `isequal to the amount of the net positive space charge within the room. Between the charge on the walls l2, ceiling, and iloorvl and the space charge suspended in the air of the room there is lan electric field. This i'leld is most intense near the walls l2, ceiling, and floor l0, but it vexists everywhereexceptat the exact center of Ethe room.

Dust parti les ina room containing ionspwill beelectrically charged, for ions attach themselves to. dust particles as soon as there is an opportunity for them to do so. l

.. ,In aroom.contannanetpstve space charge, dust particles with positive charge. areV driven by electric force toward. the walls. l2, ceiling.and floor 1.0 of the room. Thisistheoretically eVident, as explained above, and it has alsol been y experimentally demonstrated byfuafWfPen-ney and G'W. Hewitt (see ,Electrically Charged Dust in Rooms, Trans. Am. Inst. Elect. Engrs., vol. 68, pp. 278-82, 1949).

I have discovered thatan electric heater produces an excess 01.` positiveA ionsover negati-ve ions, asa result of emissionfrom the heatingelement. The amount of ion emission depends on the size,v and kind of-heater. element,l but if no provision is made to compensate for this natural emission. of anexcess of..positive ions, the ,net positive space charge within a room containing anelectric heater maybe greatly vincreased. over the'A .netV positive spacecharge inthe same room when there is no. electric heater operating.Y I have measuredV the ionization in rooms.Y with electric heaters, and have found that the positive ion; density may be increased totenv thousand or more ions per cubic centimeter.

'y Itis evident from theory, land is also demonstrated in the work by Penney and Hewitt as described in the article cited above, fthat when the space charge in aroom. .;is,increased, -as by the- Space charge ovvingtov an electric heate charged dust particles are driven morerapidly andmore forcefully toward the walls l2, ceiling, and oor l0 of that room. `I have found that the soilingandV darkening ofthe walls that isk called smudging istherebyincreased.. It is, infact, common knowledge |that thereis a tendencyfor awall I2 to smudgel alcove4 an electric heater that isset inthe wall I2 .of a room. if .the air of the room is somewhat contaminated or unclean. f

The smudging .takes-,place above theelectricy heater because thev warmth of lthe heater produces circulation of the contaminated air past this region of Wall kI2`.` The airborne particles of dust, while passing through the heater, have become positivelycharged: by attachment of positive.. ions emitted .by..the. heater element.

SODII 'aS .theS posi-tively. chargedy pal-ticles rise above the heater, they are exposed to the electric eld and are acted upon by the electric force resulting from the space charge in the room, and are driven toward the wall I2. Some strze the wall I2 forcibly and stick thereto, producing the undesirable smudge. I have found that wall smudging is caused primarily by and consists primarily of various small particles of about one micron in size.

As prevously pointed out herein, it is the purpose of my invention to reduce or eliminate such smudging. I have found that this can be done by placing certain additional elements in the electric heater for the purpose of altering or controlling the amount and polarity of the electric charge on small ions in the air that is circulated through the electric heater and exhausted from the heater into the room. These additional elements act to remove positive electric charge from some or all of the dust particles that are carried by the circulating air through the heater, and to replace the positive electric charge with negative electric charge on some or all of such dust particles.

Removing electric charge from dust particles is eiTective because dust particles that are electrically neutral will not be acted on by the electric eld of the space charge when they are discharged into the air of the room, and, therefore,

they will not be driven against the Wall by electrical force. Placing negative charge on dust particles is even more effective because when negatively charged dust particles are discharged into the room they are acted on by an electrical force that is directed not toward the wall I2 but toward the center of the room, and when such negatively charged particles are driven toward the center of the room they are not only prevented from smudging the wall but also they mix with the other charged ions in the air of the room, and since they are negatively charged whereas the net space charge in the air of the room is normally positive, they reduce the net space charge and thereby reduce the electric field that exists between the space charge and the walls I2 of the room. By thus reducing the electric iield within the room, the electric force that tends to drive other positively charged dust particles against the wall I2 is diminished, and in this way the effect of placing negative charge on a dust particle is not only to prevent that particle from being driven against the wall I2, but also to lessen the number of other particles driven against the wall I2, and the force with which such other particles may be driven against the wall I2.

To this end, I propose to place a negatively charged electrode 28 in the path of the air leaving the heater. The electric circuit, with rectier, shown in Figure 4, is one possible way of maintaining the desired negative charge on electrode 28. When dust particles with positive charge are carried through the heater by the circulation of air, some of them will be attracted by the negative charge on electrode 28. Those dust particles that come into contact with electrode 28 will lose their positive charge. The positive charge may be, and in many cases will be, replaced by negative charge, and the dust particle will then pass out into the air of the room either electrically neutral, or carrying a negative charge. This is the purpose of the invention, as explained above.

As shown in Figure 2, electrode 28 takes the form of a wire or other suitable electrical conductor in the air stream, electrically insulated' from all other parts of the heater and negatively charged. Another and even more eilective arrangement of elements is shown in Figure 3, wherein the plates 29 and 3Il are placed in the air stream. One of these plates is electrically insulated from the other parts of the heater and is negatively charged, as may be done by connecting it to the negative terminal of the recti- Iier of the circuit shown in Figure 4. The other of the two plates is electrically connected to other parts of the heater and so to ground. It is not important which of the plates 29 is negatively charged, and which is grounded. A dust particle entering the space between plates 29 and 3 I, being carried by the circulating air, may have positive charge from some natural and external source, or it may acquire positive charge by attachment of one of the positive ions emitted by the heater elements 24 and 26. In either case, every positively charged dust particle passing bee tween plates 29 and 3| will be attracted toward the negative plate. Those positively charged particles that come into contact with the negative plate will lose their positive charge and will then pass on into the room carrying either a negative charge or no charge of either sign. The dimensions of the plates are so related to the speed of circulation of the air that dust particles thus receiving a negative charge will be transported out of the space between plates 29 and 3I before they can be drawn by electrical forces against the opposing or grounded plate. Thus it is provided that many dust particles will carry a negative charge when they are transported by the circulating air into the room.

Tests have shown that either the means of Figure 2 or those of Figure 3 act to diminish smudging, the latter being the more effective.

This application is a continuation-impart of my copending application Serial No. 106,604, iled July 25, 1949, now abandoned.

I claim:

l. In an electric heater construction for discharging into a room air having substantially equal numbers of positively and negatively charged dust particles, the electric heater having a heating chamber containing a resistance heating element and into which chamber air to be heated is drawn through narrow passageways and from which chamber warm air is expelled through narrow passageways, means for shifting the balance of ion concentration of the air expelled from the heater to substantially equal positive and negative polarity comprising an electrode adjacent the heating element of said electric heater and positioned adjacent the opening from which warm air is expelled, and means for applying a constant negative charge to said electrode.

2. An electric heater for discharging into a room air having substantially equal numbers of positively and negatively charged dust particles, said heater comprising an elongated structure adapted to be positioned along the bottom of a Wall and defining an elongated heating chamber, an elongated resistance heating element in said chamber extending longitudinally thereof, said chamber being relatively narrow whereby to dene a plurality of narrow air passageways from the bottom to the top thereof, air inlet openings adjacent the bottom of said chamber and an elongated air outlet opening extending along the top of said chamber, said resistance heating element causing convection currents of 

